Problem: In this problem your goal is to sort an array consisting of n integers in at most n swaps. For the given array find the sequence of swaps that makes the array sorted in the non-descending order. Swaps are performed consecutively, one after another.

Note that in this problem you do not have to minimize the number of swaps — your task is to find any sequence that is no longer than n.

Input

The first line of the input contains integer n (1 ≤ n ≤ 3000) — the number of array elements. The second line contains elements of array: a0, a1, ..., an - 1 ( - 109 ≤ ai ≤ 109), where ai is the i-th element of the array. The elements are numerated from 0 to n - 1 from left to right. Some integers may appear in the array more than once.

Output

In the first line print k (0 ≤ k ≤ n) — the number of swaps. Next k lines must contain the descriptions of the k swaps, one per line. Each swap should be printed as a pair of integers i, j (0 ≤ i, j ≤ n - 1), representing the swap of elements ai and aj. You can print indices in the pairs in any order. The swaps are performed in the order they appear in the output, from the first to the last. It is allowed to print i = j and swap the same pair of elements multiple times.

If there are multiple answers, print any of them. It is guaranteed that at least one answer exists.

Examples

Input

5
5 2 5 1 4


Output

2
0 3
4 2


Input

6
10 20 20 40 60 60


Output

0


Input

2
101 100


Output

1
0 1

Solution (in JAVA):

Solution:
/**
 * Built using Sublime,Custom Python and Batch files
 * @author Siddhraj Sisodiya
 */

import java.io.*;
import java.util.*;
import java.math.*;

public class Main 
{
   public static void main(String[] args)
    {
        InputStream inputStream = System.in;
        InputReader in = new InputReader(inputStream);
        Task solver = new Task(in);
        solver.solve();
    }

    static class Task
    {
        InputReader in;
        long m=1000000007;
        

        Task(InputReader in)
        {
            this.in=in;
        }

        public void solve()
        {
            int n=in.nextInt();
            int arr[]=in.nextIntArray(n);
            int sortedArr[]=new int[n];
            for(int i=0;i<n;i++)
                sortedArr[i]=arr[i];
            Arrays.sort(sortedArr);
            int count=0;
            ArrayList<Pair> p=new ArrayList<>();
            for(int i=0;i<n;i++)
            {
                Pair temp=new Pair(0,0);
                if(sortedArr[i]!=arr[i])
                {
                    temp.first=i;
                    //System.out.println(arr[i]+"<----"+i);
                    for(int j=i;j<n;j++)
                    {
                        if(sortedArr[i]==arr[j])
                        {

                    //System.out.println(arr[j]+"<----"+j);
                            temp.second=j;
                            int swap=arr[i];
                            arr[i]=arr[j];
                            arr[j]=swap;
                            break;
                        }
                    }
                    count++;
                    p.add(temp);
                }
            }
            System.out.println(p.size());
            for(int i=0;i<p.size();i++)
            {
                System.out.println(p.get(i).first+" "+p.get(i).second);
            }
        }
    }

    static class Pair
    {
        public int first;
        public int second;
        public Pair(int a,int b)
        {
            first=a;
            second=b;
        }
    }

    static class InputReader 
    {
        private boolean finished = false;

        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) 
        {
            this.stream = stream;
        }

        public int read() 
        {
            if (numChars == -1) 
            {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) 
            {
                curChar = 0;
                try 
                {
                    numChars = stream.read(buf);
                } catch (IOException e) 
                {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) 
                {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int peek() 
        {
            if (numChars == -1) 
            {
                return -1;
            }
            if (curChar >= numChars) 
            {
                curChar = 0;
                try 
                {
                    numChars = stream.read(buf);
                } catch (IOException e) 
                {
                    return -1;
                }
                if (numChars <= 0) 
                {
                    return -1;
                }
            }
            return buf[curChar];
        }

        public int nextInt() 
        {
            int c = read();
            while (isSpaceChar(c)) 
            {
                c = read();
            }
            int sgn = 1;
            if (c == '-') 
            {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do 
            {
                if (c < '0' || c > '9') 
                {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() 
        {
            int c = read();
            while (isSpaceChar(c)) 
            {
                c = read();
            }
            int sgn = 1;
            if (c == '-') 
            {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do 
            {
                if (c < '0' || c > '9') 
                {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public String nextString() 
        {
            int c = read();
            while (isSpaceChar(c)) 
            {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do 
            {
                if (Character.isValidCodePoint(c)) 
                {
                    res.appendCodePoint(c);
                }
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) 
        {
            if (filter != null) 
            {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) 
        {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private String readLine0() 
        {
            StringBuilder buf = new StringBuilder();
            int c = read();
            while (c != '\n' && c != -1) 
            {
                if (c != '\r') 
                {
                    buf.appendCodePoint(c);
                }
                c = read();
            }
            return buf.toString();
        }

        public String readLine() 
        {
            String s = readLine0();
            while (s.trim().length() == 0) 
            {
                s = readLine0();
            }
            return s;
        }

        public String readLine(boolean ignoreEmptyLines) 
        {
            if (ignoreEmptyLines) 
            {
                return readLine();
            } else 
            {
                return readLine0();
            }
        }

        public BigInteger readBigInteger() 
        {
            try 
            {
                return new BigInteger(nextString());
            } catch (NumberFormatException e) 
            {
                throw new InputMismatchException();
            }
        }

        public char nextCharacter() 
        {
            int c = read();
            while (isSpaceChar(c)) 
            {
                c = read();
            }
            return (char) c;
        }

        public double nextDouble() 
        {
            int c = read();
            while (isSpaceChar(c)) 
            {
                c = read();
            }
            int sgn = 1;
            if (c == '-') 
            {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') 
            {
                if (c == 'e' || c == 'E') 
                {
                    return res * Math.pow(10, nextInt());
                }
                if (c < '0' || c > '9') 
                {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') 
            {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) 
                {
                    if (c == 'e' || c == 'E') 
                    {
                        return res * Math.pow(10, nextInt());
                    }
                    if (c < '0' || c > '9') 
                    {
                        throw new InputMismatchException();
                    }
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public boolean isExhausted() 
        {
            int value;
            while (isSpaceChar(value = peek()) && value != -1) 
            {
                read();
            }
            return value == -1;
        }

        public String next() 
        {
            return nextString();
        }

        public SpaceCharFilter getFilter() 
        {
            return filter;
        }

        public void setFilter(SpaceCharFilter filter) 
        {
            this.filter = filter;
        }

        public interface SpaceCharFilter 
        {
            public boolean isSpaceChar(int ch);
        }
        public int[] nextIntArray(int n)
        {
            int[] array=new int[n];
            for(int i=0;i<n;++i)array[i]=nextInt();
            return array;
        }
        public int[] nextSortedIntArray(int n)
        {
            int array[]=nextIntArray(n);
            Arrays.sort(array);
            return array;
        }
        public int[] nextSumIntArray(int n)
        {
            int[] array=new int[n];
            array[0]=nextInt();
            for(int i=1;i<n;++i)array[i]=array[i-1]+nextInt();
            return array;
        }
        public long[] nextLongArray(int n)
        {
            long[] array=new long[n];
            for(int i=0;i<n;++i)array[i]=nextLong();
            return array;
        }
        public long[] nextSumLongArray(int n)
        {
            long[] array=new long[n];
            array[0]=nextInt();
            for(int i=1;i<n;++i)array[i]=array[i-1]+nextInt();
            return array;
        }
        public long[] nextSortedLongArray(int n)
        {
            long array[]=nextLongArray(n);
            Arrays.sort(array);
            return array;
        }
    }
}